One stone-cold fact about Windows 7 is that we need more stone-cold facts in order to understand the new operating system that is likely to arrive in early 2010.

The company has said some of those facts will come in late October and early November during two of its major conferences — the Professional Developers Conference (Oct. 27-30) and the Windows Hardware Engineering Conference (Nov. 5-7).

What is known beyond the Windows 7 code name is that Microsoft is building the operating system on the Windows Vista code base in order to avoid the sort of application-compatibility problems that plagued Vista early in its release. The new interface will feature the Ribbon toolbar throughout, and the server version will add the much-anticipated live migration feature to the virtualization capabilities.

Sifting through the rest of the information, rumors and tidbits out there, here are seven things to know about Windows 7 before details start to emerge in advance of next month’s conferences.

1. Betas. A beta version called Milestone 3 is in the hands of testers, according to Mary Jo Foley’s “All about Microsoft” blog.

The early release is out to a select group and Foley is saying Beta 1, the first public beta, will hit by the end of the year. Other handicappers, however, say it looks like the Windows Hardware Engineering Conference (WinHEC) could be the place it is released. Others are pointing to the Professional Developers Conference (PDC) as the venue where the Windows 7 Beta 1 will be introduced. Las Vegas odds makers call that a pick ’em.

2. Final release. As far as the final release time frame, Microsoft Senior Vice President Bill Veghte sent a letter in June to enterprise and business customers saying “our plan is to deliver Windows 7 approximately three years after the January 2007 general availability launch date of Windows Vista.”

Such clarity from Microsoft is often lacking in these announcements, but pundits are interpreting Veghte’s message to mean late 2009.

In February, Bill Gates, then chief software architect, hinted at the same time frame. Some reports have said the ship date will be as early as June 2009.

3. Development. Many are asking why Microsoft has a chance of completing the operating system on such an ambitious schedule given the five years it took to get out Vista.

One major reason is Steven Sinofsky, who took over Windows development in 2006 as Vista limped to its finish line.

Sinofsky is best known for his workmanlike schedule for pumping out versions of Microsoft Office on a regular 18-month cycle. Windows 7 is Sinofsky’s next big test and perhaps his legacy at Microsoft.

4. Features. There are a few solids here, but speculation is clearly up and churning.

In May, Gates and CEO Steve Ballmer gave the first Windows 7 demonstration, showing off multi-touch screen technology.

Gates also said before his retirement in July that synchronization between Microsoft’s Live Services and Windows 7 would figure prominently, as would digital ink and speech features.

There are hints of a more modular operating system, much like Windows Server 2008 Server Core, and performance boosts. Recent screen shots from the Milestone 3 beta show the Ribbon toolbar in Wordpad and Paint. There is also evidence of new quick-install features. The glaring omission for IT is a dive into features that might make their lives easier.

5. Server version. While the client operating system is being touted as a major release (with minor revisions to the base Vista code), the server version is a minor release.

Microsoft has announced that Windows 7 will actually be what was originally planned as Windows Server 2008 R2. A few weeks ago, Microsoft confirmed that R2 would bring live migration to its virtualization platform and that the server was on-target to ship in early 2010, which would align release dates once again with the client operating system.

6. Users. Ship dates will be important.

For Vista users with Software Assurance maintenance contracts, Windows 7 is already paid for as along as it ships within the length of the contract.

Users who are still buying XP via downgrade rights through Vista Business and Ultimate will have mainstream XP support until April 14, 2009. Mainstream support includes such options as no-charge incident support, paid incident support, support charged on an hourly basis, support for warranty claims and hot-fix support. If Windows 7 ships in mid-2009, April could offer a tidy migration point to begin getting the upgrade cycle cranked up.

7. Stay tuned. Microsoft has launched a Web site called “Engineering Windows 7” that is hosted by Sinofsky and his senior engineering management colleague Jon DeVaan.

The blog has provided little in-depth information about Windows 7’s features, but Sinofsky did say a major team goal is to “promise and deliver.” Promises are what helped make Vista feel like a consolation prize.

But so far the blog has only turned up tidbits like this: “Our goal is about building an awesome release of Windows 7.”